1. [Field of the Invention]
The present invention relates to a method of generating data for parts mounters, and more particularly, to a method of constructing an automatic mounting line with automatic machines for automatically inserting or mounting parts on printed circuit board and a method of generating numerical control (NC) data for each automatic machine.
2. [Description of the Prior Art]
FIG. 4 is a diagram of a computer system which implements such a prior art method for generating NC data for hybrid printed circuit boards as disclosed in Japanese Patent Publication No. 1-100605. In the figure, reference numeral 101 represents a processor, 102 a magnetic disk unit, 103 a floppy disk drive unit, 104 a display unit, 105 a paper tape puncher, and 106 a line printer.
FIG. 5 illustrates an example of a line which is constructed of dedicated parts mounters (also called "automatic machine" hereinafter) which can mount a specific type of part.
FIG. 6 is a flow chart of the conventional method for generating NC data.
With reference to the flow chart of FIG. 6, the operation of the computer system will be described hereafter.
Parts mounting information (name of parts type; coordinates for mounting parts; mounting direction; division by insertion/mounting, by front/rear of a printed circuit board, and by each automatic machine for mounting a specific type of part) for each printed circuit board outputted from a substrate design CAD (computer aided design) system is first inputted and stored by the computer system shown in FIG. 4.
The parts mounting information is divided into three parts by insertion/mounting and front/rear of a printed circuit board: information on parts to be inserted, information on parts to be mounted on the front of a printed circuit board, and information on parts to be mounted on the rear of a printed circuit board. By each automatic machine, the divided information is further divided into units of information on parts to be mounted with each automatic machine shown in FIG. 5. The information divided by each automatic machine indicates data on which automatic machine can mount parts specified by type. Only one automatic machine is specified for each type of part. Finally, the data is converted into an NC format for each type of automatic machine to generate NC data.
The NC data generation procedure described in the foregoing is used when a line is constructed of dedicated automatic machines which can mount only a specific type of part shown in FIG. 5. The NC data is generated to enable an automatic machine 1 to mount chip parts, an automatic machine 2 to mount SOP-ICs (small outline package of integrated circuits), an automatic machine 3 to mount QFP-ICs (quad flat packages of integrated circuits) and an automatic machine 4 to mount OCs (oddly components).
Since the conventional line for mounting parts on printed circuit boards is constructed as described in the foregoing, it is impossible to balance the line if load is varied by changes in type and the number of printed circuit boards when parts are mounted on various types of printed circuit boards. With reference to FIG. 7 which explains this, it takes 40 seconds to mount an SOP-IC and an OC each on a single printed circuit board, but it takes 91 seconds to mount a chip part on the board. Therefore, it takes 91 seconds to assemble a single printed circuit board in the line. As a result, the automatic machines 2 and 4 operate for 40 seconds to mount an SOP-IC and an OC, but are idle for 51 seconds, thus reducing productivity.